I propose to investigate the role of human papillomavirus type 6 (HPV-6) in the etiology, pathogenesis, and clinical manifestations of squamous papilloma of the larynx. Laryngeal papillomata are a serious clinical problem because of their location, their resistance to treatment, their relentless recurrence, and their tendency to spread. Using recombinant DNA technology, I will isolate the four subtypes of HPV-6 genomes I have so far identified in laryngeal papilloma. The structural relationships of the genomes will be examined by comparing fine structure maps determined by analysis of restriction endonuclease digestion patterns, and by homology studies. To investigate further the origin of these viruses, the molecular epidemiology of the disease as well as the frequency of occurrence and geographical localization of the different viral subtypes will be analyzed. To investigate the biological significance of the HPV-6 subtypes, the relationship between viral subtypes and severity of disease, as manifested by the frequency of surgical intervention and tracheobronchial extension of disease, will be determined. On the basis of fine structure mapping and homology studies, I will determine if the virus found in laryngeal papillomata are the same as the HPV-6 subtypes I have already molecularly cloned from genital warts. If it can be established that the same virus is the etiological agent for genital warts and laryngal papilloma, then it would suggest several possible modes of transmission, and consequently, preventive measures. I will investigate the state (extrachromosomal and/or integrated) and quantity of the viral genome in lesions by Southern transfer analysis. The distribution of the viral genome in lesions will be determined by in situ hybridization and the distribution of HPV capsid antigen will be determined by an immunoperoxidase technique. This will determine if the proliferation and cytopathology of the epidermal cells result from a productive infection in a few cells or the presence of HPV-6 DNA in most of the cells. To investigate the role of viral gene expression in the pathogenesis of laryngeal papilloma, viral transcripts will be examined by Northern and S1 nuclease techniques. These molecular analyses of the papillomavirus in larynegeal papillomatosis are aimed at contributing to preventive measures and to the understanding of viruses which infect humans.